The present invention relates to a camera based apparatus for safeguarding a machine and to a camera unit that can advantageously be used in such an apparatus. In particular, the invention relates to a camera unit and apparatus for safeguarding a machine having a first machine part performing a working movement relative to a second machine part, such as a press brake or similar bending, cutting or stamping machine.
DE 10 2007 004 724 A1 describes a prior art apparatus. The apparatus comprises a light source and a camera unit that are designed to be disposed on the right and left of a punch of a bending press, so that so that they are concurrently moved during the working movement of the punch. The concurrently moving light source produces a light beam running parallel to the leading edge of the punch and directed to the likewise concurrently moving camera unit on the opposite end. The camera unit receives the light beam and in this way can directly monitor the spatial region in front of the leading edge of the pressing tool. An intrusion into the monitored spatial region during the working movement is detected and typically results in stopping the working movement, in particular by switching off power to the bending press.
The mechanical design of a suitable camera unit is also described in DE 10 2007 004 724 A1. The camera unit includes an objective with an objective body and an electronic image sensor arranged on a component support. The objective body and the component support are connected by means of a coupling mechanism to form an integrated assembly. The coupling mechanism has two defined movement capabilities that enable a coupling part to be displaced relative to the objective body on the one hand and relative to the component support on the other hand. By means of two releasable clamping mechanisms, the two movement capabilities can be enabled or blocked independently of each other. This enables very accurate adjustment of the image sensor relative to the objective in various directions.
The good adjustment capability of the image sensor is however accompanied by a complex design. In particular, a complex multi-part design of the coupling mechanism is necessary for the provision of the two independent movement capabilities. Wear of said parts can result in the clamping mechanisms loosening under high loading, or as a result of strong shocks or vibrations. The result of this is that detection errors can occur and readjustment is necessary at regular intervals. In addition, the complex design places high requirements on manufacturing, whereby in turn the manufacturing costs of such a camera unit increase. It is thus desirable to provide a simpler camera unit for an apparatus of the afore-mentioned type.